Injection and hemostasis site

ABSTRACT

A pad of elastomeric material having a softness of no more than about durometer 50 Shore 00. The pad may carry adhesive and/or a housing for adhering the pad to a surface, either directly or indirectly through an envelope which surrounds the pad and carries the adhesive. Such a pad exhibits hemostatic and leak prevention properties against needle puncture holes in the skin or the wall of a hollow medical device. Particularly, hemostasis may be prevented with low pressure application of the pad to the skin. The pad may be previously applied to the skin of the patient or a wall of a medical device such as tubing or a solution bag, and the needle may then penetrate both the pad and the skin or medical device wall, to make a resealable puncture with leakage reduction and hemostasis when the needle is withdrawn.

This is a continuation-in-part of U.S. patent application Ser. No.10/943,106, filed Sep. 16, 2004 now U.S. Pat. No. 8,017,826.

BACKGROUND OF THE INVENTION

Generally, when the needle or catheter penetrates the skin for access toan artery, a vein, or a fistula as in hemodialysis, there is a certainamount of bleeding that takes place when it is removed. In blooddonation, for example, when the donor needle is removed, the donor isasked to elevate his or her arm and to press cotton gauze against theneedle penetration site for some minutes, until the wound has completelyclotted.

In the field of extracorporal blood processing such as hemodialysis,larger diameter needles, such as 15 gauge needles, are used rather thanthe smaller needles used for blood collection and blood sampling. Theblood pressure is higher due to the fistula's arterialized veinstructure, and the patient is anticoagulated for the extracorporealprocedure. Thus, when the needle is withdrawn, bleeding is morepronounced, and must be dealt with more rigorously, to avoid the loss ofa significant amount of blood through bleeding. Since hemodialysis inparticular is performed frequently on chronic patients, even small bloodlosses can add up, so that it would be desirable to minimize thebleeding to avoid the relatively small amount of blood that isconventionally lost when dialysis needles are withdrawn.

Generally, compression is used for a period of time after withdrawal ofany hollow bore needle, to achieve hemostasis. Typically, this is donewith absorbent gauze manually pressed over the cannulation site as soonas the needle is removed. As the gauze is absorbent, this method doesnot staunch bleeding, but merely creates a slowing of the blood leakageso the body's natural clotting mechanisms can eventually take over andstop the blood flow. In hemodialysis, it is not uncommon to use five orsix successive gauze compressions over a period of 20-30 minutes untilhemostasis is achieved.

The prior art also discloses non absorbent materials to stop cannulationsite bleeding. One way of accomplishing this was proposed in McRae etal. U.S. Pat. No. 4,233,980, where a pressure bladder made of flexible,non-elastic material and carried on a rigid, floor mounted arm ispressed against a site to produce hemostasis after an arterial puncture.Another way was proposed in Stanulis U.S. Pat. No. 4,182,338 where askin contacting surface as soft as 25 Shore A durometer is part of astrap arrangement around the portion of the body where blood loss is tobe prevented by compression of the skin contacting surface. Another wayis Roth U.S. Pat. No. 5,263,965 which comprises a rigid disc as a manualcompression aid.

Another significant problem with hollow bore needle cannulation iscannulation-induced infection to the cannulation tract and/or vessel.Although the needle is sterilized at the time of manufacture, and ismaintained sterile in its package, needles may become unsterile as soonas its sterility protector is removed. At this stage it is susceptibleto being contaminated by touch or air-borne bacteria. Or, the act ofcannulation may drag into subcutaneous tissues bacteria from the skinsurface or near-surface dermal layers. While the skin is disinfectedwith various chemicals, this is typically a relative rather thanabsolute disinfection, and bacteria will dwell on, or just under, thedead layer of skin cells of the cannulation site. It is known in thefield of thoracic surgery to control infection induced by scalpels andthe like, by laying over the disinfected skin area intended for surgicalcutting a sheet of sterile plastic. This sheet is pressed against theskin, to which it adheres without adhesive. Not only is the outersurface of the sheet a sterile field on which surgical instruments maybe placed without contamination, but the sheet's adherence to the skintends to immobilize bacteria on the skin and under the dead skin cells.Owing to the clarity of the film, it is possible for the surgeon tovisualize the cutting area and cut through the film as he/she surgicallycuts the patient. Thus, no or few bacteria are dragged into the surgicalsite during cutting due to the effect of the sterile sheet. Tegaderm isa brand name of this prior art product.

Besides cannulating patients, needles also cannulate injection sitescarried on medical devices, such as tube sets, drug vials, IV bags andthe like. The prior art injection sites all comprise elastomeric bungsof a hardness not less than about 10 Shore A durometer, and are carriedin typically plastic housings that hold the bung fixed and undercompressive forces both for sealing the space between the bung and thehousing, but also to urge shut the slit caused by a cannulating needle,when removed. Many elastomers are not suitable for injection sitesbecause they either are either cored out when cannulated with a sharp,beveled hollow bore needle, or they leak through the cannulated sliteven in the presence of the compressive forces urged on it by thehousing. It has not been known until now of a resealable, non-coringelastomeric material that did not require a compressive or retentiverigid housing to be effectively resealable after passage and removal ofneedles, including hollow bore sharp needles.

Another problem of injection sites is that they must be manufacturedinto the medical device. For example a dialysis set typically comprisesthree or more injection sites at various locations on the set. Sincemany sites are never used during a particular medical procedure, thecost of manufacturing injection sites in every medical device, when onlya few are used, represents a great monetary waste. It would beadvantageous if a simple, cheap, attachable injection site to medicaldevices could be developed.

DESCRIPTION OF THE INVENTION

By this invention, a supersoft, typically elastomeric, pad or sheet isdisclosed as an improved replacement for gauze squares, and other modesof achieving hemostasis on any bleeding site, whether by cannulationwith needles of any size, or trauma from gunshot wounds and the like.Its action is the same. The typically substantially nonporous-surfacedpad stops the bleeding and promotes clotting, being a solid, pore freepad, or a porous pad typically having at least one, nonporous, skin likesurface. The nonporous, skin like surface lies against the bleedingsite, for hemostasis. The pores, if present, may be closed cells, orinterconnected, open cells if desired, to contribute to softness of thepad. “Pores” are spaces in the pad which are large enough to pass bloodor other medical fluid. The pad may be provided in a package inmedically clean, or preferably sterile, condition. The pad may, in someembodiments, comprise a pair of opposed, parallel, equally sized majorfaces, forming a flat sheet, for simplicity of manufacture.

In the case of cannulation with a needle or catheter, the pad is placedagainst the cannulation site either before or immediately after thecannula is removed, and improves on gauze in two major ways. First, itis not absorbent of blood from the bleeding cannulation site, so muchless blood is lost when it is pressed against the cannulation site toseal off the cannulation slit or hole. Second, because the supersoftelastomer can sealingly conform to even the micro nooks and crannies ofthe skin with extremely low or even essentially no applied force, whichforce can be applied manually, or by tape, or any appliance alone or incombination or in serial order, the vessel underlying the cannulationsite is not likely to be damaged or pressed shut. Our lab tests showthat after cannulating an in vitro vascular model with a 15 g needle andmaintaining the fluid pressure within the vascular model at about 80mmHg (the pressure of a strong hemodialysis graft access), a force ofover 200 gms applied to gauze squares over the (now-removed 15G needle)cannulation site incision slows, but does not stop fluid flow out of thecannulation site, thus mimicking clinical experience with gauze. But byusing a pad of supersoft elastomer of a durometer of no more than about50 Shore 00, and preferably less than about 30 Shore 00, we were able toabsolutely stop flow immediately from the cannulation site with only anapplied holding pressure of about 25 gms. Because of the delicate natureof fistulae and grafts, and their tendency to stenose, such reducedforce and immediate cessation of bleeding is a great advance. Thesupersoft elastomers conformal nature at low forces gives it greatadvantage as a pad, to be manually held and applied to a cannulationsite and to be clear (transparent) for direct visualization of thebleeding site underneath the pad without having to remove the pad, as isthe case with the prior art. There is a risk in the prior art ofremoving an opaque, hemostasis appliance before full clotting isattained, causing unnecessary blood loss from the patient.

Durometer measurements made herein are in accordance with ASTM DurometerHardness Standard D2240-03.

Preferably, the pad may be supplied sterile.

The pad may be large enough to cover any size wound. For example, in thecase of gunshot wounds or military trauma, the wound may exceed manysquare inches in bleeding area. Blood loss from such wounds can be sorapid that bleeding must be stopped prior to evacuating a patient to ahospital. One method to do this is to pour a clotting agent directlyinto the wound, for example flaked chitosan. This agent soaks up bloodand provides enhanced surface area for rapid clotting. However, theclotted chitosan is difficult and time consuming to remove, once thepatient is in the hospital, and the clotted blood within the chitosan isnot available for harvesting by any one of the known, autologoustransfusion methods. It is therefore an advantage for a large wound tobe covered by a sheet of the material used in this invention, as itssupersoft nature conforms to the nooks and crannies of the skin and thewound boundaries, requiring little or no applied pressure to sealagainst blood loss, and retaining blood which may be harvested later andreturned to the vascular system. Sheets or pads of this invention can beapplied within the body or wound to seal off bleeding arteries orvessels directly, so as to limit or stop internal bleeding. Because thesheet is preferably clear and self-sealing, medical workers can passmedical instruments through the sheeting without removing it.

This invention relates to a particular form of elastomeric pad which maybe adhered (applied) to the skin of a patient or to the exterior of amedical device (such as a tube or bag wall) at a desired cannulationsite, either prior to or after the actual injection. In someembodiments, the elastomeric pad may be clear, soft and thin enough,typically on the order of 2 to 5 or 7 millimeters, so that thecannulation site of a patient may be palpitated through the alreadyin-place pad prior to cannulation, in order to find an underlying vesselor medical device by touch so as to maintain the sterility of thepatient's intended cannulation site. The elastomeric pad may be coatedwith disinfectant, or it may be applied to pre-disinfected skin, oralternatively, to a wall of a medical device such as a solution bag ortubing, before cannulation, or applied after withdrawal of the cannulato prevent bleeding without necessarily continuing applied, strongexternal pressure.

Upon cannulation, an advancing needle or catheter can if desired passfirst through the elastomeric pad, and then into the skin of the patientor material of the medical device, typically into a vascular system ofthe patient or lumen of the medical device. Upon withdrawal of thecannula, the pad exhibits the surprising property of resealing without acompressive housing, and provides significant suppression of bleeding orfluid leakage, with a consequent increase of hemostasis in a patient (orsuppression of leakage from the medical device), with significantly lessneed for compression to facilitate the hemostasis. Also, the cannulationsite on the skin (or medical device) may be subjected to anti-microbialeffect due to the presence of an antiseptic at the junction between thepad and the skin or medical device. Many suitable anti-microbialantiseptics are quite volatile, and the pad of this invention provides aphysical barrier that increases the term of active disinfection byreducing the evaporation rate of the antiseptic material, such asalcohol. Pores in the pad, if any, can be used to store antiseptic, thusextending the contact time of the antiseptic around the wound as itdiffuses through the pad material to the wound area. Bacteria on orwithin the skin or medical device may also be immobilized by the pad,and thus prevented from being drawn in through the skin or medicaldevice by the advancing cannula. Thus, aseptic conditions can bepromoted during the time that the cannula resides in the skin. Also,hemostasis with less or even virtually no added pressure can be achievedafter withdrawal of the cannula. Then, the elastomeric pad can beremoved when hemostasis has fully taken place, and when it can beexpected that there will be no further spontaneous bleeding.

Thus, reduction of blood loss can be achieved, particularly in thesituation of chronic patients, where access to the vascular system musttake place frequently. This invention can also work with freshcannulation sites or repeat cannulation sites, commonly known as“buttonhole” sites.

Accordingly, a method is provided which comprises the method ofsuppressing bleeding through the skin of a patient which comprises:applying to the skin of the patient a soft pad of typically elastomericmaterial having a hardness of no more than about durometer 50 Shore 00to suppress the bleeding. Resealability of the pad to a needle puncturemay be provided if the soft pad is an elastomeric material. However,soft (no more than about Durometer 50 Shore 00), non-elastomericmaterials such as polyethylene foam pads may be used for effectivebleeding suppression in those circumstances where a needle puncture isnot used. The elastomer or non-elastomer pad used may either be a solid,pore free pad, or a porous pad typically having at least one,non-porous, skin-like surface, unless the material of the pad is ofblood repellant material or the pores are small enough so that blooddoes not substantially enter into them, or the pores are separated as ina closed-cell foam, so that the pores may be used to impart softness tothe pad, without significant seepage of blood through the pad.

Typically, materials as soft as or softer than Durometer 30 Shore 00 maybe used with good effect.

The soft pad may have a non-porous surface for abutting the skin or awall of a medical fluid container which has the required hardness of nomore than about Durometer 50 Shore 00. Optionally, other portions of thepad may be harder, to provide support and the like.

If desired, after the soft pad is applied, one may pass a medical needlethrough the elastomeric pad into the tissue of the patient, andthereafter withdraw the needle with substantially suppressed bleeding.

In this circumstance, in some embodiments the elastomeric material ofthe pad may have a hardness of no more than about durometer 30 Shore 00,for example 10 Shore 00 or less.

Alternatively, the needle or hollow cannula may be inserted through apoint of the skin of the patient, and, thereafter, the soft, paddescribed above may be placed on the skin of the patient to cover thepoint of the skin through which the cannula penetrates. Thereafter, thecannula or needle is removed.

Also, a soft, elastomeric pad described above may be applied to the wallof a hollow medical device such as a plastic solution bag. One thenpasses a medical needle through the pad and the wall of the hollowmedical device, and thereafter withdraws the needle, with leakagethrough the hole formed in the wall by the needle being suppressed. Herealso in some embodiments the elastomeric material of the pad may have ahardness of no more than about durometer 30 Shore 00, for example 10Shore 00 or less.

An “elastomer” is defined as a rubbery material having at least onehundred percent elongation to break, and which snaps back tosubstantially its original configuration when released from stretching,like rubber. An elastomer is not a gel, which has little or no abilityto snap back toward an original configuration after stretching.

Further, in accordance with this invention, a method is provided whichcomprises the step of: applying a pad to the skin of a patient or amedical device, the pad consisting essentially of an elastomer or otherflexible material having a hardness of no more than essentiallydurometer 50 Shore 00 and preferably no more than durometer 30 Shore 00.Wounds can thus be sealed to stop bleeding, and, similarly, punctureleakage in a medical device can also be stopped.

The material of the pad preferably has a high elongation to break,typically at least about 500% or preferably about 900% to 1000% or more.Such an elastomer exhibits high resealability, so that the needlepuncture hole does not readily leak blood at natural blood pressures,particularly from an artery, vein, or fistula, optionally without acompressive or retentive housing as in the prior art of injection sitescarried on medical tube sets. Also, the elastomeric material, althoughvery soft, tends to be non-coring to conventional medical needles. Thus,a stick—on injection site may be provided by this invention.

In some embodiments, the elastomer pad has a thickness of about 0.1-0.5cm., and has a hardness of no more than about 50 Shore 00 durometer, andpreferably no more than 30 Shore 00, the elastomer material being nonflowable.

In some embodiments, the elastomers of this invention comprise an oilplasticized material such as an oil-plasticized block copolymercomprising (A) at least one crystalline, aryl-containing polymersegment, and (B) at least one elastomeric, aliphatic polymer segment.Some plasticized elastomers of this type are disclosed in U.S. Pat. No.5,508,334 of John Y. Chen, and numerous other patents by the sameinventor, and also in U.S. Pat. No. 5,994,450 of Tony M. Pearce, thedisclosures of which are incorporated by reference herein.

In some embodiments, the crystalline, aryl-containing polymer segmentcomprises monoalkenylarylene polymer units such as styrene oralphamethylstyrene. The elastomeric, aliphatic polymer segment mayconsist essentially of isoprene and butadiene polymer units in someembodiments.

The pad so used may be coated on one side with a skin adhesive anddirectly adhered to the skin, so that preferably the exterior of the padhas no adhesive. Or an adhesive may be mixed into the material, or be abasic attribute of the tacky material. However, in other embodiments,the pad may be carried under a cloth, or a non-woven fabric or plasticstrip, or a length of adhesive tape as in a “Bandaid” ™ arrangement, theelastomer pad being a replacement for the gauze pad of a “Bandaid”dressing. The strip may preferably carry a hole, thus exposing the pad,which may be transparent, where cannulation is intended. The pad may becarried in or on a single sheet or within a multi-sheet envelope, whichenvelope also may comprise plastic sheeting, for example, thermoplasticsheets of polyethylene, pvc, polyurethane, or similar materials,particularly when the adhesive desired is not compatible with, or doesnot adhere well to the elastomeric pad. The sheet or envelope carriesthe skin adhesive on one side thereof to adhere the pad to the skin ofthe patient. The pad may be at least partially melted so the materialentwines with a cloth or non-woven or plastic material adhered to astrip. Preferably the pad will not detach from the skin or medicaldevice until desired. Preferably this adherent, adhesive device willprevent leakage from the cannulation site between the skin (or medicaldevice) and the pad, when the needle has been removed.

As stated above, in some embodiments, the envelope, when used, maydefine a central opening to expose the pad carried therein. For example,the envelope may have a pair of opposed, major faces, with each facedefining a central opening, typically aligned with each other, to exposethe pad carried therein.

Some embodiments of the materials used as plasticized elastomers maycomprise a high viscosity poly (styrene-ethylene-butylene-styrene)triblock copolymer having styrene end blocks and ethylene and butylenecenter blocks in a ratio preferably within a range of about 20:80 toabout 40:60, as described in Chen U.S. Pat. No. 5,508,334, column 5. Thepolymer, when blended in a melt with an appropriate amount ofplasticizing oil, may comprise a gelatinous elastomer composition havingin some embodiments a relatively high elongation to break of at leastabout 1600%, and a tear resistance of at least about 300,000 or 500,000dynes per centimeter, with substantially complete, rubbery snap backwhen extended to about 1200% elongation, as called for in the cited Chenpatent. Ultimate tensile strength may in some embodiments be at leastabout 800,000 dynes per square centimeter, having a low elongation setat break of substantially not greater than about two percent.

Other suitable materials are Versaflex CL2003x thermoplastic elastomer,sold by GLS Corporation of McHenry, Ill., and Dermasol DS309 ofCalifornia Medical Innovations, of Pomona, Calif.

Alternatively, silicone or polyurethane formulations of the propersoftness, with or without plasticizers, may be used.

Surprisingly, it has been found that many of the materials of theabove-cited patents, and other soft materials, exhibit excellent andunexpected hemostatic or leak resistance characteristics when adhered toan injection location such as a patient's skin or a medical device, withthe added advantage that needle coring is suppressed by these materials,despite their softness and resealing of the needle slit despite lackinga compressive housing.

Further in accordance with this invention, a pad of elastomeric materialfor hemostasis may be provided, the pad having a softness of no morethan about durometer 50 Shore 00. The pad further defines, in someembodiments, at least one and preferably a pair of integral retentionstraps, which are made of the elastomeric material and which form onepiece with the pad, being typically co-molded with the pad. Thethickness of the pad is in some embodiments at least twice, andtypically three or more times, the thickness of the retention straps.

It is preferred for the hardness of the elastomeric material to be nomore than about durometer 30 Shore 00, and for the elastomer to have anelongation to break of at least about 500%.

Such a pad with straps may be used for hemostasis by wrapping the padaround the arm or leg of a patient, overlapping the retention strapsalong a portion of their length. As they wrap around the arm or leg,this overlapping may take place at any circumferential point on the armor leg spaced from the location of the pad. Typically this overlappingtakes place at a diametrically opposed area of the arm or leg from thelocation of the pad. Thus, the pad can be retained in position on theskin of the patient by natural tack adhesion between the retentionstrips. In that position, the pad may provide hemostasis to acannulation site of a freshly withdrawn needle or catheter, and may beretained in position for as long as necessary while providing only alittle degree of compression, and effecting good hemostasis whilepreventing bleeding from the hole in the patient's tissue left behind bythe needle or catheter. This hemostasis can even be effective to causehemostasis in catheter access sites where connection has been made to anartery.

Further in accordance with this invention, a method comprises: insertinga hollow cannula through the point in the skin of a patient and into ablood vessel; thereafter placing a soft, elastomeric pad on the skin ofthe patient to cover the point of the skin through which the cannulapenetrates; and thereafter removing the cannula. The pad in question isas described above, having a hardness of no more than about durometer 50Shore 00, and typically less than 30 Shore 00, whereby bleeding issuppressed by the pad. This method greatly facilitates the prevention ofbleeding upon withdrawal of the hollow cannula from the blood vessel, inthat, while insertion of the cannula into the blood vessel can be doneconventionally, the pad of this invention can then be placed over theskin of the patient at the point of cannula penetration, and the highresilience and softness of the elastomeric pad can immediately suppressbleeding upon withdrawal of the cannula, without any significantbleeding taking place while the pad is being applied after removal ofthe cannula.

The soft, elastomeric pad may be affixed to the skin of the patientusing preferably substantially transparent tape.

Furthermore, advantageously, in some embodiments the pad may be of asolid, domed shape. The term “dome” or “domed” implies an elastomericstructure having a rounded, convex, outer surface, in which a centralportion of the elastomeric pad is substantially thicker than peripheralportions. Specifically, the central portion may be at least twice asthick as the peripheral portion of the pad at the edge of the pad. Theedge of the pad may have a thickness tapering to essentially zero, or itmay connect to an integral strap or outer flange.

The pad of this invention, for example the pad of solid, domed shapedescribed above, may reside in a recess defined by a wall of a plasticsheet. The sheet also has a flat flange at least partly surrounding therecess, with the flat flange being affixed to the skin of a patient withtape, adhesive, or the like, and with the recess wall and the patient'sskin together enclosing the soft, elastomeric pad, while the pad abutsthe skin. The plastic sheet wall with its recess may comprise acontainer which is manufactured in a manner similar to known,single-serving jelly containers used in restaurants, and in which a flatflange surrounding the recess may be covered with a peel sheet which ismanually removable, in the manner of a single-serving jelly container.Also, the flat flange may be affixed to the skin through an adhesivelayer carried on the flange.

The plastic sheet may be made of poly(ethylene-vinyl acetate), or anyother desired plastic material. The recess (such as a dome-shapedrecess), may be cold formed in the plastic sheet.

Furthermore, as described previously, the hardness of the elastomer maypreferably be no more than about durometer 30 Shore 00, while theelongation to break for the elastomer may preferably be at least about800 percent, and the tear resistance may in some embodiments be at leastone million dynes per cm. Also, the elastomeric pad may have aglass—smooth, flat face, which may be placed in contact with the skin.

The lower limit of hardness for an elastomer that may be used in apractical manner in accordance with this invention varies to an extentdepending upon the pressure of blood (or fluid in a medical container).Higher pressure fluids generally are better sealed with an elastomerwhich has a hardness that is somewhat greater than may be required inthe circumstance where fluid pressures are lower, although by thisinvention the hardness is no more than about 50 Shore 00 in anycircumstance, relating to sealing of blood pressure and of the walls ofmedical fluid containers. For example, a somewhat softer material candesirably be used for the sealing of a venous puncture than may berequired for the sealing of an arterial puncture.

In some embodiments, the elastomeric pad may slightly overfill therecess in the plastic sheet, so that an outer portion thereof projectsbeyond the plastic sheet, to provide firm contact with the skin,particularly when the elastomeric pad is placed in contact with the skinwithout removal from the recess of the plastic sheet, to assure goodskin contact. Alternatively, the elastomeric pad may be removed from therecess for use.

Thus, bleeding may be effectively controlled by applying the typicallyelastomeric pad of this invention to a wound, such as at the point wherea cannula is inserted through the skin, using, in some embodiments, asoft pad of elastomeric material having a hardness of no more thandurometer 50 Shore 00, with the pad being of solid, dome shape with aflat bottom.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a pad of an embodiment of thisinvention.

FIG. 2 is a plan view of a pad of an embodiment of this invention,carried on an adhesive coated sheet of plastic.

FIG. 3 is a transverse sectional view showing the pad of an embodimentof this invention secured in an envelope defined by a pad of plasticsheets, which are normally peripherally secured together, but shown inseparated fashion for clarity, forming an envelope which contains thepad of this invention.

FIG. 4. is a perspective view of a pad of an embodiment of thisinvention placed over a large trauma wound.

FIG. 5 is an elevational view of another embodiment of this invention,showing a pad with an integral strap.

FIG. 6 is an elevational view, taken in section, showing a needlepenetrating the skin, with a dome-shaped pad of this invention overlyingthe entrance point of the needle through the skin and secured there byan adhesive sheet member.

FIG. 7 is a plan view of FIG. 6.

FIG. 7A is a modified version of FIG. 7.

FIG. 8 is a perspective view of an elastomeric, dome-shaped pad, carriedin a dome-shaped recess which is defined by a dome wall of a plasticsheet, which sheet also has a flat flange surrounding the dome wall, andshowing a removable peel tab used to enclose the pad until use isrequired.

FIG. 9 is an inverted, sectional view, taken in elevation, of thedome-shaped elastomeric pad of FIG. 8, carried in the dome-shaped recessof the plastic sheet, and shown adhered to the skin of a patient, withthe dome wall of the plastic sheet and the patient's skin togetherenclosing the soft, elastomeric pad.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to FIG. 1, a pore-free pad of very soft elastomer 10 is shown,preferably having a coating of adhesive 12 on its lower face foradhesion to the skin. Pad 10 has a softness of less than durometer 30Shore 00. It can be manufactured in accordance with the teachings ofPearce U.S. Pat. No. 5,994,450, for example comprising apolystyrene-hydrogenated poly (isoprene and butadiene)-polystyrenecopolymer, plasticized with either mineral oil or a combination ofmineral oil and resin. Other suitable materials for manufacture of thepad of this invention are manufactured, for example, by Edizone, LC, aUtah Limited Liability Company of Pleasant Grove, Utah. Other suitablematerials may comprise, for example DS309 Dermasol, manufactured byCalifornia Medical Innovations of Pomona, Calif. Typically, the softness(hardness) of materials used for the pad 10 may be no more than aboutdurometer 60 Shore 000, all according to tests according to the ASTMDurometer Hardness Standard D2240-03, and they may even be so soft as tonot register on the Shore 00 scale and registrable only on an extremelysoft scale according to a “gram bloom” test or the Shore 000 scale. Grambloom involves the applied force necessary to depress a 10 mm diameterflat probe 4 mm into a sample of elastomer.

It is also sometimes desirable for the material used in this inventionto have a tear strength of at least about 800,000 dynes per cm, and anelongation to break of said elastomer of at least about 900%.

Pad 10 may be adhered to the skin 14 of a patient, after the skin hasbeen wiped with an antiseptic such as povidone iodine or an alcohol suchas isopropanol. The pad may be applied while the antiseptic is stillpresent on the skin, so as to trap the antiseptic against the skin. Anyappropriate antiseptic may be used, and the antiseptic may be carried onor in pad 10, if desired. An increased-viscosity or gelled antisepticmay also be used, for example the antiseptic of patent Publication No.US 2003-0175323 A1.

Pad 10 may be of any desired dimension in length and width, blanket sizeto button size, and may be of rectangular shape, or nonrectangularshape, such as circular or oval, if desired. It may have a thickness ofabout 0.2-0.3 cm, which may be thin enough to feel the presence of avein 16 through pad 10 by means of finger touch, because of the extremesoftness of the elastomer material of pad 10. Then, a needle may beinserted in normal manner through pad 10 to penetrate vein 16 for aconventional IV injection process, which may include large volumes ofparenteral solution, blood collection, or extracorporeal bloodprocessing, with the needle penetrating pad 10 at point 18. Pad 10 isdesirably substantially transparent for visualization of the skinunderneath.

When the needle is withdrawn, point 18 recloses, and substantiallyreseals to prevent leakage of blood out of vein 16. Furthermore, suchultra soft material, preferably of relatively high tear resistance (tearstrength of over two million dynes) and relatively high elongation tobreak, is resistant to coring by an injection needle, so that hole 18recloses and reseals, optionally with gentle manual pressure, to anextent sufficient to prevent pressurized blood (or other fluid) leakagethrough hole 18. Also, because of the adhesive attachment of pad 10,little blood leaks transversely from the puncture hole in the skinlaterally between the skin and the adhering material of pad 10.

Alternatively, pad 10 may be applied immediately after withdrawing of aneedle (or catheter) that penetrates the skin, such as a fistula needle,to suppress bleeding. For example, in hemodialysis and otherextracorporeal blood treatment procedures, when a fistula needle iswithdrawn from the patient, substantial bleeding takes place because ofthe larger diameter of fistula needles (and similarly with certain otherextracorporeal blood flow access needles or catheters). Thus, aspreviously described herein, it is normal that special procedures forsuppressing bleeding must take place when those needles and cathetersare withdrawn. By this invention, pad 10 can be used to avoid thosepreviously-necessary special procedures as described above, while alsoresulting in reduced blood loss.

The pad 10 of this invention may be of a small, button-like size ofabout one to six centimeters diameter or the like, particularly when itis desired to suppress the bleeding after withdrawal of a needlelikecannula, whether or not the pad is applied before penetration of thecannula, or after the cannula has been withdrawn. Also, pad 10 may beused to seal larger, laparoscopic catheter holes in a patient, or holeswhich are formed in arterial walls by cardiac angiography catheters,angioplasty catheters, electronic mapping or ablation catheters, and allother medical devices which cause bleeding when they are withdrawn. Acurrent, recommended procedure for the suppression of bleeding after thewithdrawal of catheters and the like from the vascular system ispressure with the use of a sandbag for about three hours. The pad ofthis invention may serve as a substitute for this, being firmly appliedto the resulting wound after withdrawal of a catheter, blockingbleeding, but permitting the patient to be mobile, and suppressing, orpreferably completely eliminating, bleeding.

Instead of using adhesive 12, pad 10 may be applied to the patient inany desired, conventional manner including adhesive tape, a conventionalclamp, a tie around an arm or a leg, or even manually, if that isappropriate.

Furthermore if desired, pad 10 may comprise a relatively large mat orblanket of the soft elastomer material, optionally being thicker thanspecific thicknesses recommended for other uses above, for example athickness of about 0.5 cm or greater, and a length and width each of atleast about 10 cm, to provide a bleeding suppression blanket, tosuppress bleeding from larger wounds such as bullet and knife wounds, orother severe lacerations, providing a mode of first aid to suppressexternal bleeding of an injured patient. The weight of a thicker blanketof the material of this invention can provide sealing force without theneed for added application of pressure, although such added pressure mayof course be applied by any desired means, such as tying the pad to thepatient, or the use of weights or manual pressure. Furthermore, such aform of pad 10, being of relatively greater thickness, such as athickness of 1-5 cm. and being of pillowcase or blanket size, can beprewarmed, to provide a bleeding suppression blanket that can wrap thepatient in whole or in part, and also addresses the issue of shock byproviding positive warmth to the patient. Also, a hot water chamber maybe provided in the pad, like a form of hot water bottle.

Also, when pad 10 is in the form of a thick blanket for bleedingsuppression, it may carry an adhesive on one side for direct adhesion tothe skin of the patient, with the adhesive providing further suppressionof bleeding and migration of blood between pad 10 and the skin, or itsnatural tack may be used to retain the pad blanket 10 on the skin.

Furthermore, pad 10, in all its forms, tends to cause the clotting totake place directly in the needle track or the other injury, with theresult that there are fewer bacteria in the scab which forms, and opensthe possibility of less scarring.

Vitamin E oil and/or another anti-scarring agent or other medicament maybe added to elastomer formulation of this invention, for release to theskin surrounding the injury, and the injury itself, such as the needletrack. Also, other medicaments may be provided to the formulation of pad10, either as a separate layer, or integrally mixed within the materialof the pad itself. For example, clotting agents may be added to promoteclotting, such as collagen.

The material of this invention may contain other agents as well, forexample, clotting (hemostatic) agents such as collagen and other knownmaterials, including simple, inorganic salts and other promoters forblood clotting particularly outside of the body. Other examples ofpossible clotting agents include: Aluminum Ammonium Sulfate, AluminumPotassium Sulfate. Chitosan, Epinephrine, (1:50,000-1:1,000), TannicAcid, Collagen, Styptic Collodion, Hyaluronic Acid, Sodium Hyaluronate,Aluminum Sulfate, Cotarine, Cotarine Chloride, and Cotaminium Chloride.

In some embodiments, the surface of solid, nonporous pad 10 which facesthe skin (or any other surface which is being sealed) may beglass-smooth, to promote engagement of the ultra soft pad material withirregularities in the skin or other surface, to promote sealing and toprevent the flow of blood or other fluid from the hole being sealedlaterally between the pad and the skin or other surface.

Remarkably, it has been found that the materials of which pad 10 can bemade as described herein generally do not need to be substantiallycompressed to reseal from needle sticks. Thus, while they may be used ina housing, they do not require a housing in many uses, and a housing inwhich they are contained does not have to hold them under compression toobtain desirable results, although such compression may be used ifdesired.

The shape of pad 10 of course is not limited: it may comprise a roundbutton, or a rectangular one of diameter or other transverse dimensionof one or more centimeters, or, as stated above, it may comprise a largeblanket of appropriate size to address severe lacerations, and to atleast partially wrap the patient, being heated if desired to addressshock while also suppressing external bleeding.

Accordingly, a stick-on injection site and/or hemostasis site isprovided, which can be applied when an injection is required, and whichfacilitates aseptic conditions, reducing the drawing of bacteria intothe body as the cannula advances through the skin, and providing goodhemostasis at normal blood pressures.

Alternatively, skin 14 could be a wall of a plastic solution container,a plastic tube, or the like, with the same sealing characteristic beingachieved, providing a penetrable injection site for a needle.

Turning to FIG. 2, pad 10 a, similar to pad 10, is carried on anadhesive plastic strip 20, with adhesive layer 22 on at least a portionof the underside of strip 20 permitting adherence as shown of strip 20and pad 10 a to the skin 24 of a patient, which alternatively maycomprise the wall of a solution bag, or an apertured tubing wall overwhich pad 10 a extends, or the like. Plastic strip 20 can carry adhesiveto adhere to the skin or wall 24. Also, the periphery 26 of pad 10 a canadhere to the same or a different kind of adhesive carried on theunderside of plastic strip 20 to position pad 10 a in fixed mannercovering an aperture 28 formed in plastic strip 20.

Alternatively, FIG. 3 shows an embodiment that looks substantiallyidentical in plan view to the embodiment of FIG. 2, in which anelastomeric pad 10 b is attached to plastic strip 20 b and retainedthere by a peripheral adhesive 30. Also, an optional, additional plasticstrip 32 may serve to form an enclosing envelope by a peripheral sealwith plastic strip 20 b, enclosing elastomeric pad 10 b. Such seals maybe peripheral seals at areas 34. Bottom plastic strip 32 may carry anadhesive layer 36 for adhesion to the skin and an upper, peripheraladhesive layer 38 for retention and positioning of pad 10 b within theenvelope 37 defined between plastic strips 20 b and 36.

Preferably, each plastic strip defines an aperture 28 b, 40 to exposeboth sides of pad 10 b. Pad 10 b, carried within its envelope 37, isexposed for finger palpitation to find a blood vessel under the skin inthe case where adhesion to the skin is desired, and generally for openneedle access through pad 10 b and the wall or patient's skin to whichit is adhered by means of the envelope 37.

Generally, upon withdrawal of a needle, the puncture which is formed inthe respective pads 10, 10 a, 10 b reseals without significantcompression because of the unique physical characteristics of thematerial used as the elastomer.

A specific example of silicone material which may be used to form thepad of this invention is Rhodia 40022 reinforced silicone gel. Softersilicones than this material may also be used, if they retain thecharacteristics of a nonflowing elastomer.

Alternatively, pad 10 may be applied or adhered to the skin byconventional taping, with the center of the pad left exposed for needlepenetration, so that an adhesive layer 12 is not needed. The naturaltack of pad 10 may provide some skin adhesion to seal against bloodflow.

When the elastomeric material is plasticized with a (preferablymetabolizable) lubricating oil, it may be possible to cannulate throughthe pads 10, 10 a, 10 b with a non-siliconized needle, in which theneedle picks up enough lubricant from the disk to desirably reduce theforce of cannulation in a manner comparable with a siliconized needle,to avoid the use of siliconized needles.

As an additional feature, pads 10, 10 a, 10 b may contain enoughimpregnated antiseptic, one such example being isopropanol, so that theinner surface of the pad, lying against the skin, will have an alcoholcontent sufficient for continuing antimicrobial effect. Alternatively, alayer of an alcohol-containing gel may be preapplied to the skin 14, andthen pad 10 may be applied to the skin and, if desired, taped inposition to provide a stick-on injection site. Such alcohol-containinggels are described in Utterberg U.S. Patent Publication US 2003/0175323A1. Or, a porous pad with a solid skin can have the pores filled withalcohol or another antimicrobial agent, for continued antibacterialeffect.

Referring to FIG. 4, a patient 50 who has suffered a severe laceration52 may be treated by immediate care personnel in the field by simplyclosing the laceration and covering it with an enlarged pad 10 c made inaccordance with this invention. Pad 10 c may comprise a soft,transparent elastomer material as described above. A specific materialused for pad 10 c and other pads may be Dermasol DS309, comprising astyrene-ethylene/butylene-styrene copolymer which carries more than 50%of mineral oil as a plasticizer. The particular DS309 material has adurometer of about 20-30 Shore 000, an ultimate elongation (elongationto break) of about other pads in accordance with this invention) maycomprise 15-20% of styrene-ethylene/butylene-styrene copolymer; 80-85%of mineral oil USP; 0.1-0.3% of antioxidant; and 4 parts/per million/ofVitamin E, this being a formulation published for Dermasol by CaliforniaMedical Innovations.

Pad 10 c may be of any appropriate shape or size, and may have anydesired thickness, for example, from 0.2 cm. to 1 cm. Pad 10 c has anatural tack so that, if desired, it can spontaneously be retained overthe wound site 52. Alternatively, it may be held by tape or straps, asdesired, to hold blood in the wound site and to promote hemostasis(clotting). If desired, a hemostasis (clotting) agent as described abovemay be applied, or such a hemostasis agent may be carried as a layer onthe inner face of pad 10 c, or may be an ingredient in the elastomerformulation of pad 10 c to leak out into the wound to promote clotting.

Referring to FIG. 5, a pad 56 is shown, being made of an elastomericmaterial in accordance with this invention, such as Dermasol DS309, andfurther defining a pair of integral retention straps 58, 60 which aremade of the same elastomeric material and which form one piece with thepad, having been preferably molded with the pad in a single step. Thethickness of the pad 56 can be seen in this embodiment to be about fiveor six times greater than the thickness of the retention straps. Pad 56,with integral straps 58, 60, may be carried on a relatively stiffbacking strip 62 for storage, from which it may be removed for use.

This pad may be used by being placed on an arm or leg of the patientover a needle or catheter injection site, before or after insertion andwithdrawal of the needle or a catheter introducer device. Then, afterwithdrawal of the needle or catheter, pad 56 can reseal, to facilitatehemostasis, and also it prevents blood leakage.

Pad 56 can be attached by stretching the straps 58, 60 around the arm orleg of the patient, causing portions of the straps to overlap, typicallyat a diametrically opposed portion of the arm or leg from the positionof the pad on the skin. The natural, adhesive tack of the straps canprovide desired adhesion to each other, holding the pad in place on thearm or leg without added adhesive. Alternatively, an adhesive or othertechnique may be used to hold the straps in position.

Referring to FIGS. 6 and 7, a soft, elastomeric pad 70 is of dome shape,and is made of a soft, elastomeric material as described above,preferably having a Durometer of no more than about 50 Shore 00, andpreferably no more than about Durometer 30 Shore 00.

In the embodiment shown in FIGS. 6 and 7, needle 72 penetrates the skin74 at point 76, the needle being representative of any desired cannulaused for obtaining access to the body including needles for access tothe vascular system of the patient such as fistula needles.Alternatively, catheters may be used as desired and as discussed above.

In this particular embodiment, before needle 72 is withdrawn, domed pad70 is laid over needle entrance point 76 of the needle into the skin ofthe patient. A rectangular cover sheet 78, having an inner-adhesivelayer 80, overlies domed pad 70, as further illustrated in FIG. 7.Basically, sheet 78 is a rectangular section of adhesive tape or thelike.

When a rectangular form of adhesive sheet 78 is provided as shown inFIG. 7, a portion 82 of the sheet around needle 72, carried by needlehub 73, may remain open as shown, particularly in FIG. 6, in theimmediate area around the needle so that, after pad 70 has been placedover needle penetration point 76, needle 72 can be withdrawn, and theportion 82 of cover 78 may be manually pressed down onto the skin 74 toprovide a seal of wound 76 caused by the needle and to suppressbleeding.

Alternatively, as shown in FIG. 7A, elastomeric pad 70 may be laid downas shown in FIG. 6 over the wound 76 caused by needle 72, but with thecover sheet 78 a overlying pad 70 being in the form of a narrower strip,so that at least one edge 84 of pad 70 is effectively laterally exposed,without interference by the adhesive tape cover 78 a, so that needlewithdrawal 72 is easier, and with less pain.

Other pads which are not of dome shape may also be used in thisinvention.

Turning to FIGS. 8 and 9, an elastomeric pad 70 a of dome shape can fitinto a plastic housing 86, which is formed from a plastic sheet having adome-shaped recess defined by a dome wall 88 of the plastic sheet, withthe plastic sheet also defining a flat flange 90 surrounding dome wall88. The dome wall and recess may also be of other shapes as desired.

A removable peel covering 92 may be conventionally applied to theplastic sheet package 86 to seal elastomeric pad 70 a until the time ofuse.

The basic technology may be similar to that technology which is used tomanufacture single serving jelly containers used in restaurants, exceptthat, in this embodiment, the recess is dome shaped. However, othershapes for container 86 may be utilized, including the conventionalshape of a restaurant jelly container. If desired, an adhesive may beplaced on the outer face of flange 90, to facilitate connection with theskin.

If desired, after opening by peeling away covering 92, soft, elastomericpad 70 a may be removed and placed on the skin in the manner indicatedin FIGS. 6 through 7 a. Alternatively, elastomeric pad 70 a may beretained in container 86 and placed on the skin 74 a along withcontainer 86, as illustrated in FIG. 9. If desired, elastomeric pad 70 amay have a flat face 89 which is slightly elevated above the face offlange 90 when peel layer 92 is removed (as shown in FIG. 8) so that,when placed on the skin 74 a as in FIG. 9, there may be a desirable,slight compression. This compression may be provided by adhesion offlange 90 to the skin or as shown, by the application of tape strips 94to flange 90. Package 86 with its attached, soft, elastomeric pad 70 amay be placed on the skin while a needle is penetrating to cover wound76 or, alternatively, package 86 and/or pad 70 a may be placed on theskin after withdrawal of the needle or other cannula, to cover theresulting wound left behind by the withdrawn needle or cannula. Forexample, a wound from an angioplasty catheter or the like may be coveredby pads 70, 70 a, or a hemodialysis needle wound may be covered by pads70, 70 a.

The plastic sheet of container 86 may be made of poly(ethylene-vinylacetate) (called EVA), polyethylene, or the like. EVA bonds todesirable, plasticized materials that form pad 70 a, and container 86may carry adhesive for adhesion to the skin, and/or may provide a goodconnection with removable cover 92. Also, the poly(ethylene-vinylacetate material) can be cold-formed to form the desired container 86.The pad may typically be easily removable when container 86 is made ofpolyethylene.

As shown in FIG. 9, the recess wall 88 of container 86 and the patient'sskin 74 a together enclose soft, elastomeric pad 70 a, with the pad ofabutting the skin. Container 86 may be secured to the skin by adhesivetape 94.

Pads 70 and 70 a may be made, for example, from Versaflex®CL 2003XThermoplastic Rubber Compound, which is a proprietary, oil-plasticizedstyrene block copolymer elastomer, manufactured by GLS Corp. of McHenry,Ill. This is a transparent material having a Shore 00 hardness of about29, an elongation at break of about 1290% (ASTM D412—Die C, 2 hours at23° C.); a tear strength of about 7 million dynes per cm. (ASTM D624); atensile strength (English) of 280 psi (ASTM D412—Die C—2 hours at 23°C.); a 100% modulus (English) of about 9 psi (ASTM D 412—Die C, 2 hoursat 23° C.) and a 300% modulus of about 15 psi (English) ASTM D 412—DieC, 2 hours at 23° C.). Medicaments, such as clotting agents,disinfectants, or any medically beneficial material may be added to theformulation, if desired.

The pads of this invention may desirably be as clear and transparent asglass so that the wound underneath may be easily monitored withoutremoval of the pad.

Thus, a stick-on injection site or hemostasis device is provided, inwhich the pad through which injection may be made, if desired, does nothave to be retained under compression in a housing to obtain goodresealing, although it may be so retained if desired. Accordingly, thepad-type injection site or hemostasis device does not require a rigidhousing to hold it in a compressed state, but the pad simply providesspontaneous resealing under most physiological blood pressureconditions, thus greatly reducing loss of blood. Such a pad typeinjection site is also usable to provide an injection site through awall of a medical device, while providing good resealing after theneedle is withdrawn. Also, typically larger pads of this invention maybe used for hemostasis of larger wounds.

The above has been offered for illustrative purposes only, and is notintended to limit the scope of the invention of this application, whichis as defined in the claims below.

That which is claimed is:
 1. A method of suppressing bleeding at aneedle insertion site, comprising the steps of: inserting a hollowcannula through a point in skin in a vessel of a patient; thereafterplacing a soft, elastomeric pad on the skin of the patient to cover thepoint of the skin through which the cannula penetrates into the vessel;and thereafter removing the cannula while simultaneously compressing thepad toward said point in the skin by a force insufficient to collapsethe cannulated vessel, said pad having a hardness of no more than aboutdurometer 50 Shore 00, whereby bleeding is immediately terminated andclotting is promoted by the pad.
 2. The method of claim 1 is which thesoft, elastomeric pad is affixed to the skin of the patient, and the padis substantially transparent.
 3. The method of claim 1 in which the padis of a solid, domed shape.
 4. The method of claim 3 in which said padof solid, domed shape resides in a dome-shaped recess defined by a domewall of a plastic sheet, said sheet also having a flat flange at leastpartially surrounding said dome wall, said flat flange being affixed tothe skin of the patient, with the dome wall and the patient's skintogether enclosing the soft, elastomeric pad, and the pad abutting theskin.
 5. The method of claim 4 in which said flat flange is affixed tothe skin through an adhesive layer carried on the flange.
 6. The methodof claim 4 in which said plastic sheet is made of poly(ethylene-vinylacetate).
 7. The method of claim 4 in which said dome-shaped recess iscold formed in said plastic sheet.
 8. The method of claim 4 in which thehardness of said elastomer is no more than about Durometer 30 Shore 00.9. The method of claim 8 in which said elastomer has a tear resistanceof at least about 800,000 dynes per cm.
 10. The method of claim 9 inwhich an elongation to break of said elastomer is at least about 500percent.
 11. The method of claim 1 in which said pad has a glass-smoothface in contact with the skin.
 12. The method of claim 1 in which saidpad resides in a recess, defined by a recess wall of a plastic sheet,said sheet also having a flat flange at least partially surrounding saidrecess wall, said flat flange being affixed to the skin of the patient,with the recess wall and the patient's skin together enclosing the soft,elastomeric pad, and the pad abutting the skin.
 13. The method of claim12 in which said flat flange is affixed to the skin through an adhesivelayer carried on the flange.
 14. The method of claim 12 in which saidplastic sheet is made of poly(ethylene-vinyl acetate).
 15. The method ofclaim 1 in which the soft, elastomeric pad is affixed against the skinby an adhesive member extending over the pad on the skin to press thepad against the skin.
 16. The method of claim 15 in which the pad issubstantially transparent.
 17. A flexible, hemostasis pad having a flatnon-porous surface immediately terminating bleeding upon application ofsaid flat, non-porous surface to a bleeding vessel at a pressureinsufficient to collapse said bleeding vessel, said pad having arounded, convex outer surface, and a hardness of no more than aboutdurometer 50 Shore 00, wherein a central portion of said pad is at leasttwice as thick as a peripheral portion of the pad at the edge of thepad.
 18. A flexible, hemostasis pad having a non-porous surfaceimmediately terminating bleeding upon application of said pad to ableeding vessel at a pressure insufficient to collapse said bleedingvessel, said pad having a rounded, convex outer surface, and a hardnessof no more than about durometer 50 Shore 00, the pad being substantiallytransparent, wherein a central portion of said pad is at least twice asthick as a peripheral portion of the pad at the edge of the pad.
 19. Thepad of claim 18 in which said non-porous surface is a flat surface. 20.A flexible, hemostasis pad having a non-porous surface immediatelyterminating bleeding upon application of said pad to a bleeding vesselat a pressure insufficient to collapse said bleeding vessel, said padhaving a rounded, convex outer surface, and a hardness of no more thanabout durometer 50 Shore 00, wherein the pad comprises an elastomericmaterial, and said pad is substantially transparent and has a centralportion which is substantially at least twice as thick as a peripheralportion of the pad at the edge of the pad.
 21. The pad of claim 20 inwhich the non-porous surface is a flat surface.
 22. A method ofsuppressing bleeding at a needle insertion site, comprising the stepsof: inserting a hollow cannula through a point in the skin of a patientto cannulate a vessel; positioning a nonporous surface of asubstantially transparent, soft pad against the skin of the patient tocover the point on the skin through which the cannula penetrates, andthereafter removing the cannula, while simultaneously during the removalprocess pressing said pad against said point and surrounding skin with aforce insufficient to collapse the cannulated vessel, said pad beingsubstantially transparent and having a hardness of no more than aboutdurometer 50 Shore 00, whereby bleeding from said point is immediatelyterminated and clotting is promoted by the pad.
 23. The method of claim22 in which said pad has a rounded, convex outer surface.
 24. The methodof claim 22 in which a central portion of the pad is at least twice asthick as a peripheral portion of the pad at the edge.
 25. The method ofclaim 24 in which the pad pressing against the skin at and surroundingthe patient is accomplished by an adhesive bearing strap attached to thepatient.
 26. The method of claim 24 in which said pad pressing againstthe skin at and surrounding said point is accomplished manually.
 27. Thepad of claim 22 in which the non-porous surface is a flat surface.